"Once they had a chance to actually examine the currency, they could see that it wasn't right," said Sgt. Cord Wood with the Corvallis Police Department. "They don't figure out until after the person's gone that it's counterfeit money."

Officers in Corvallis and Albany are working the cases.

Their advice for Craigslist sellers: Give cash a good look.

"Take the time to examine the money. look at it closely. Look at those things that will tip you off whether it's a legit bill or not," Wood said.